During the territorial shifts as a result of World War I, the formerly german and now Polish port city of Danzig (gdansk) became a semi-autonomous city-state from 1920 to 1939. As an important trade hub, Danzig quickly developed its own Aviation companies, which were sprouting all over greatly due to Hugo Junkers' revolutionary F. 13 design. Most aircraft operated in Danzig sported the two white crosses on red background from the city's coat of arms on wings and rudder.